JavaScriptCore-903.tar.gz

[apple/javascriptcore.git] / runtime / JSString.cpp

diff --git a/runtime/JSString.cpp b/runtime/JSString.cpp
index 48391de1f9edbdaa7e4e88f52be611429cf7d9ea..da15997d32db78aed7b57f07f0cc4b529331f010 100644 (file)
--- a/runtime/JSString.cpp
+++ b/runtime/JSString.cpp
@@ -24,62 +24,291 @@
 #include "JSString.h"
 
 #include "JSGlobalObject.h"
 #include "JSString.h"
 
 #include "JSGlobalObject.h"

+#include "JSGlobalObjectFunctions.h"

 #include "JSObject.h"
 #include "JSObject.h"

+#include "Operations.h"

 #include "StringObject.h"
 #include "StringPrototype.h"
 
 namespace JSC {
 #include "StringObject.h"
 #include "StringPrototype.h"
 
 namespace JSC {

+    
+static const unsigned substringFromRopeCutoff = 4;
+
+const ClassInfo JSString::s_info = { "string", 0, 0, 0 };

 
 

-JSValuePtr JSString::toPrimitive(ExecState*, PreferredPrimitiveType) const
+void JSString::resolveRope(ExecState* exec) const

 {
 {

-    return const_cast<JSString*>(this);
+    ASSERT(isRope());
+
+    UChar* buffer;
+    if (PassRefPtr<StringImpl> newImpl = StringImpl::tryCreateUninitialized(m_length, buffer))
+        m_value = newImpl;
+    else {
+        outOfMemory(exec);
+        return;
+    }
+
+    RopeImpl::Fiber currentFiber = m_fibers[0];
+
+    if ((m_fiberCount > 2) || (RopeImpl::isRope(currentFiber)) 
+        || ((m_fiberCount == 2) && (RopeImpl::isRope(m_fibers[1])))) {
+        resolveRopeSlowCase(exec, buffer);
+        return;
+    }
+
+    UChar* position = buffer;
+    StringImpl* string = static_cast<StringImpl*>(currentFiber);
+    unsigned length = string->length();
+    StringImpl::copyChars(position, string->characters(), length);
+
+    if (m_fiberCount > 1) {
+        position += length;
+        currentFiber = m_fibers[1];
+        string = static_cast<StringImpl*>(currentFiber);
+        length = string->length();
+        StringImpl::copyChars(position, string->characters(), length);
+        position += length;
+    }
+
+    ASSERT((buffer + m_length) == position);
+    for (unsigned i = 0; i < m_fiberCount; ++i) {
+        RopeImpl::deref(m_fibers[i]);
+        m_fibers[i] = 0;
+    }
+    m_fiberCount = 0;
+
+    ASSERT(!isRope());

 }
 
 }
 

-bool JSString::getPrimitiveNumber(ExecState*, double& number, JSValuePtr& value)
+// Overview: this methods converts a JSString from holding a string in rope form
+// down to a simple UString representation.  It does so by building up the string
+// backwards, since we want to avoid recursion, we expect that the tree structure
+// representing the rope is likely imbalanced with more nodes down the left side
+// (since appending to the string is likely more common) - and as such resolving
+// in this fashion should minimize work queue size.  (If we built the queue forwards
+// we would likely have to place all of the constituent StringImpls into the
+// Vector before performing any concatenation, but by working backwards we likely
+// only fill the queue with the number of substrings at any given level in a
+// rope-of-ropes.)    
+void JSString::resolveRopeSlowCase(ExecState* exec, UChar* buffer) const

 {
 {

-    value = this;
-    number = m_value.toDouble();
-    return false;
+    UNUSED_PARAM(exec);
+
+    UChar* position = buffer + m_length;
+
+    // Start with the current RopeImpl.
+    Vector<RopeImpl::Fiber, 32> workQueue;
+    RopeImpl::Fiber currentFiber;
+    for (unsigned i = 0; i < (m_fiberCount - 1); ++i)
+        workQueue.append(m_fibers[i]);
+    currentFiber = m_fibers[m_fiberCount - 1];
+    while (true) {
+        if (RopeImpl::isRope(currentFiber)) {
+            RopeImpl* rope = static_cast<RopeImpl*>(currentFiber);
+            // Copy the contents of the current rope into the workQueue, with the last item in 'currentFiber'
+            // (we will be working backwards over the rope).
+            unsigned fiberCountMinusOne = rope->fiberCount() - 1;
+            for (unsigned i = 0; i < fiberCountMinusOne; ++i)
+                workQueue.append(rope->fibers()[i]);
+            currentFiber = rope->fibers()[fiberCountMinusOne];
+        } else {
+            StringImpl* string = static_cast<StringImpl*>(currentFiber);
+            unsigned length = string->length();
+            position -= length;
+            StringImpl::copyChars(position, string->characters(), length);
+
+            // Was this the last item in the work queue?
+            if (workQueue.isEmpty()) {
+                // Create a string from the UChar buffer, clear the rope RefPtr.
+                ASSERT(buffer == position);
+                for (unsigned i = 0; i < m_fiberCount; ++i) {
+                    RopeImpl::deref(m_fibers[i]);
+                    m_fibers[i] = 0;
+                }
+                m_fiberCount = 0;
+                
+                ASSERT(!isRope());
+                return;
+            }
+
+            // No! - set the next item up to process.
+            currentFiber = workQueue.last();
+            workQueue.removeLast();
+        }
+    }

 }
 
 }
 

-bool JSString::toBoolean(ExecState*) const
+void JSString::outOfMemory(ExecState* exec) const

 {
 {

-    return !m_value.isEmpty();
+    for (unsigned i = 0; i < m_fiberCount; ++i) {
+        RopeImpl::deref(m_fibers[i]);
+        m_fibers[i] = 0;
+    }
+    m_fiberCount = 0;
+    ASSERT(!isRope());
+    ASSERT(m_value == UString());
+    if (exec)
+        throwOutOfMemoryError(exec);

 }
 
 }
 

-double JSString::toNumber(ExecState*) const
+// This function construsts a substring out of a rope without flattening by reusing the existing fibers.
+// This can reduce memory usage substantially. Since traversing ropes is slow the function will revert 
+// back to flattening if the rope turns out to be long.
+JSString* JSString::substringFromRope(ExecState* exec, unsigned substringStart, unsigned substringLength)

 {
 {

-    return m_value.toDouble();
+    ASSERT(isRope());
+    ASSERT(substringLength);
+    
+    JSGlobalData* globalData = &exec->globalData();
+
+    UString substringFibers[3];
+    
+    unsigned fiberCount = 0;
+    unsigned substringFiberCount = 0;
+    unsigned substringEnd = substringStart + substringLength;
+    unsigned fiberEnd = 0;
+
+    RopeIterator end;
+    for (RopeIterator it(m_fibers.data(), m_fiberCount); it != end; ++it) {
+        ++fiberCount;
+        StringImpl* fiberString = *it;
+        unsigned fiberStart = fiberEnd;
+        fiberEnd = fiberStart + fiberString->length();
+        if (fiberEnd <= substringStart)
+            continue;
+        unsigned copyStart = std::max(substringStart, fiberStart);
+        unsigned copyEnd = std::min(substringEnd, fiberEnd);
+        if (copyStart == fiberStart && copyEnd == fiberEnd)
+            substringFibers[substringFiberCount++] = UString(fiberString);
+        else
+            substringFibers[substringFiberCount++] = UString(StringImpl::create(fiberString, copyStart - fiberStart, copyEnd - copyStart));
+        if (fiberEnd >= substringEnd)
+            break;
+        if (fiberCount > substringFromRopeCutoff || substringFiberCount >= 3) {
+            // This turned out to be a really inefficient rope. Just flatten it.
+            resolveRope(exec);
+            return jsSubstring(&exec->globalData(), m_value, substringStart, substringLength);
+        }
+    }
+    ASSERT(substringFiberCount && substringFiberCount <= 3);
+
+    if (substringLength == 1) {
+        ASSERT(substringFiberCount == 1);
+        UChar c = substringFibers[0].characters()[0];
+        if (c <= maxSingleCharacterString)
+            return globalData->smallStrings.singleCharacterString(globalData, c);
+    }
+    if (substringFiberCount == 1)
+        return new (globalData) JSString(globalData, substringFibers[0]);
+    if (substringFiberCount == 2)
+        return new (globalData) JSString(globalData, substringFibers[0], substringFibers[1]);
+    return new (globalData) JSString(globalData, substringFibers[0], substringFibers[1], substringFibers[2]);

 }
 
 }
 

-UString JSString::toString(ExecState*) const
+JSValue JSString::replaceCharacter(ExecState* exec, UChar character, const UString& replacement)

 {
 {

-    return m_value;
+    if (!isRope()) {
+        size_t matchPosition = m_value.find(character);
+        if (matchPosition == notFound)
+            return JSValue(this);
+        return jsString(exec, m_value.substringSharingImpl(0, matchPosition), replacement, m_value.substringSharingImpl(matchPosition + 1));
+    }
+
+    RopeIterator end;
+    
+    // Count total fibers and find matching string.
+    size_t fiberCount = 0;
+    StringImpl* matchString = 0;
+    size_t matchPosition = notFound;
+    for (RopeIterator it(m_fibers.data(), m_fiberCount); it != end; ++it) {
+        ++fiberCount;
+        if (matchString)
+            continue;
+
+        StringImpl* string = *it;
+        matchPosition = string->find(character);
+        if (matchPosition == notFound)
+            continue;
+        matchString = string;
+    }
+
+    if (!matchString)
+        return this;
+
+    RopeBuilder builder(replacement.length() ? fiberCount + 2 : fiberCount + 1);
+    if (UNLIKELY(builder.isOutOfMemory()))
+        return throwOutOfMemoryError(exec);
+
+    for (RopeIterator it(m_fibers.data(), m_fiberCount); it != end; ++it) {
+        StringImpl* string = *it;
+        if (string != matchString) {
+            builder.append(UString(string));
+            continue;
+        }
+
+        builder.append(UString(string).substringSharingImpl(0, matchPosition));
+        if (replacement.length())
+            builder.append(replacement);
+        builder.append(UString(string).substringSharingImpl(matchPosition + 1));
+        matchString = 0;
+    }
+
+    JSGlobalData* globalData = &exec->globalData();
+    return JSValue(new (globalData) JSString(globalData, builder.release()));

 }
 
 }
 

-UString JSString::toThisString(ExecState*) const
+JSString* JSString::getIndexSlowCase(ExecState* exec, unsigned i)

 {
 {

-    return m_value;
+    ASSERT(isRope());
+    resolveRope(exec);
+    // Return a safe no-value result, this should never be used, since the excetion will be thrown.
+    if (exec->exception())
+        return jsString(exec, "");
+    ASSERT(!isRope());
+    ASSERT(i < m_value.length());
+    return jsSingleCharacterSubstring(exec, m_value, i);

 }
 
 }
 

-JSString* JSString::toThisJSString(ExecState*)
+JSValue JSString::toPrimitive(ExecState*, PreferredPrimitiveType) const

 {
 {

-    return this;
+    return const_cast<JSString*>(this);

 }
 
 }
 

-inline StringObject* StringObject::create(ExecState* exec, JSString* string)
+bool JSString::getPrimitiveNumber(ExecState* exec, double& number, JSValue& result)

 {
 {

-    return new (exec) StringObject(exec->lexicalGlobalObject()->stringObjectStructure(), string);
+    result = this;
+    number = jsToNumber(value(exec));
+    return false;

 }
 
 }
 

-JSObject* JSString::toObject(ExecState* exec) const
+bool JSString::toBoolean(ExecState*) const
+{
+    return m_length;
+}
+
+double JSString::toNumber(ExecState* exec) const

 {
 {

-    return StringObject::create(exec, const_cast<JSString*>(this));
+    return jsToNumber(value(exec));
+}
+
+UString JSString::toString(ExecState* exec) const
+{
+    return value(exec);
+}
+
+inline StringObject* StringObject::create(ExecState* exec, JSGlobalObject* globalObject, JSString* string)
+{
+    return new (exec) StringObject(exec->globalData(), globalObject->stringObjectStructure(), string);
+}
+
+JSObject* JSString::toObject(ExecState* exec, JSGlobalObject* globalObject) const
+{
+    return StringObject::create(exec, globalObject, const_cast<JSString*>(this));

 }
 
 JSObject* JSString::toThisObject(ExecState* exec) const
 {
 }
 
 JSObject* JSString::toThisObject(ExecState* exec) const
 {

-    return StringObject::create(exec, const_cast<JSString*>(this));
+    return StringObject::create(exec, exec->lexicalGlobalObject(), const_cast<JSString*>(this));

 }
 
 bool JSString::getOwnPropertySlot(ExecState* exec, const Identifier& propertyName, PropertySlot& slot)
 }
 
 bool JSString::getOwnPropertySlot(ExecState* exec, const Identifier& propertyName, PropertySlot& slot)


@@ -88,9 +317,13 @@ bool JSString::getOwnPropertySlot(ExecState* exec, const Identifier& propertyNam
     // This function should only be called by JSValue::get.
     if (getStringPropertySlot(exec, propertyName, slot))
         return true;
     // This function should only be called by JSValue::get.
     if (getStringPropertySlot(exec, propertyName, slot))
         return true;

+    if (propertyName == exec->propertyNames().underscoreProto) {
+        slot.setValue(exec->lexicalGlobalObject()->stringPrototype());
+        return true;
+    }

     slot.setBase(this);
     JSObject* object;
     slot.setBase(this);
     JSObject* object;

-    for (JSValuePtr prototype = exec->lexicalGlobalObject()->stringPrototype(); !prototype.isNull(); prototype = object->prototype()) {
+    for (JSValue prototype = exec->lexicalGlobalObject()->stringPrototype(); !prototype.isNull(); prototype = object->prototype()) {

         object = asObject(prototype);
         if (object->getOwnPropertySlot(exec, propertyName, slot))
             return true;
         object = asObject(prototype);
         if (object->getOwnPropertySlot(exec, propertyName, slot))
             return true;


@@ -99,54 +332,40 @@ bool JSString::getOwnPropertySlot(ExecState* exec, const Identifier& propertyNam
     return true;
 }
 
     return true;
 }
 

-bool JSString::getOwnPropertySlot(ExecState* exec, unsigned propertyName, PropertySlot& slot)
+bool JSString::getStringPropertyDescriptor(ExecState* exec, const Identifier& propertyName, PropertyDescriptor& descriptor)

 {
 {

-    // The semantics here are really getPropertySlot, not getOwnPropertySlot.
-    // This function should only be called by JSValue::get.
-    if (getStringPropertySlot(exec, propertyName, slot))
+    if (propertyName == exec->propertyNames().length) {
+        descriptor.setDescriptor(jsNumber(m_length), DontEnum | DontDelete | ReadOnly);

         return true;
         return true;

-    return JSString::getOwnPropertySlot(exec, Identifier::from(exec, propertyName), slot);
-}
-
-JSString* jsString(JSGlobalData* globalData, const UString& s)
-{
-    int size = s.size();
-    if (!size)
-        return globalData->smallStrings.emptyString(globalData);
-    if (size == 1) {
-        UChar c = s.data()[0];
-        if (c <= 0xFF)
-            return globalData->smallStrings.singleCharacterString(globalData, c);

     }
     }

-    return new (globalData) JSString(globalData, s);
-}

     
     

-JSString* jsSubstring(JSGlobalData* globalData, const UString& s, unsigned offset, unsigned length)
-{
-    ASSERT(offset <= static_cast<unsigned>(s.size()));
-    ASSERT(length <= static_cast<unsigned>(s.size()));
-    ASSERT(offset + length <= static_cast<unsigned>(s.size()));
-    if (!length)
-        return globalData->smallStrings.emptyString(globalData);
-    if (length == 1) {
-        UChar c = s.data()[offset];
-        if (c <= 0xFF)
-            return globalData->smallStrings.singleCharacterString(globalData, c);
+    bool isStrictUInt32;
+    unsigned i = propertyName.toUInt32(isStrictUInt32);
+    if (isStrictUInt32 && i < m_length) {
+        descriptor.setDescriptor(getIndex(exec, i), DontDelete | ReadOnly);
+        return true;

     }
     }

-    return new (globalData) JSString(globalData, UString::Rep::create(s.rep(), offset, length));
+    
+    return false;

 }
 
 }
 

-JSString* jsOwnedString(JSGlobalData* globalData, const UString& s)
+bool JSString::getOwnPropertyDescriptor(ExecState* exec, const Identifier& propertyName, PropertyDescriptor& descriptor)

 {
 {

-    int size = s.size();
-    if (!size)
-        return globalData->smallStrings.emptyString(globalData);
-    if (size == 1) {
-        UChar c = s.data()[0];
-        if (c <= 0xFF)
-            return globalData->smallStrings.singleCharacterString(globalData, c);
-    }
-    return new (globalData) JSString(globalData, s, JSString::HasOtherOwner);
+    if (getStringPropertyDescriptor(exec, propertyName, descriptor))
+        return true;
+    if (propertyName != exec->propertyNames().underscoreProto)
+        return false;
+    descriptor.setDescriptor(exec->lexicalGlobalObject()->stringPrototype(), DontEnum);
+    return true;
+}
+
+bool JSString::getOwnPropertySlot(ExecState* exec, unsigned propertyName, PropertySlot& slot)
+{
+    // The semantics here are really getPropertySlot, not getOwnPropertySlot.
+    // This function should only be called by JSValue::get.
+    if (getStringPropertySlot(exec, propertyName, slot))
+        return true;
+    return JSString::getOwnPropertySlot(exec, Identifier::from(exec, propertyName), slot);

 }
 
 } // namespace JSC
 }
 
 } // namespace JSC